In a mobile communication system, applications that communicate a large amount of data such as those for streaming video data have been utilized. For this reason, technologies to improve a data communication speed in a mobile communication system have been researched. For example, as an example of such a technology, a Coordinated multi-point transmission/reception (CoMP) technology which simultaneously uses a plurality of cells for communication and Carrier Aggregation (CA) which simultaneously uses a plurality of frequency bands for communication have been proposed. The CoMP and CA technologies have been studied in Long Term Evolution-Advanced (LTE-Advanced) which is a communication standard, the standardization thereof having been made by Third Generation Partnership Project (3GPP).
In a mobile station that is in communication, when a handover occurs, for example, a mobile station measures cell radio strength and quality of frequency bands, which a base station specified for the mobile station, to measure quality or strength of received radio signals, then the mobile station reports to the base station identification numbers of cells which have sufficient signal strength and quality to be used for communication. Furthermore, in a mobile communication system implementing the CoMP or CA technology, the cell radio strength and quality is also measured when a cell or a frequency band to be used by a mobile station is added. Thus, a frequency at which a mobile station measures quality and strength of radio signals and a frequency at which measurement results are reported to a base station increase.
On the other hand, a technology is proposed in which power consumption and time for performing cell search by a mobile station are suppressed and complexity involved in design and administration is simplified (for example, refer to Japanese Laid-open Patent Publication No. 2001-119745). In the technology disclosed in Japanese Laid-open Patent Publication No. 2001-119745, by using grouped channel identifiers received from sectors, a mobile station which communicates with a plurality of base stations determines the sectors for use in communication. In this technology, channel identifiers which belong to a same group are assigned to sectors in a same base station. Then, the base station notifies visiting mobile stations of, for one of neighboring base stations, any one of channel identifies assigned to sectors of the one of neighboring base stations and of a group number to which the channel identifier belongs.